Summary
The FAA proposes to adopt a new airworthiness directive (AD) for certain The Boeing Company Model 757 airplanes. This proposed AD was prompted by reports of several occurrences of a power transfer unit (PTU) control valve that failed to open when commanded. This proposed AD would require installing new relays and changing certain wire bundles leading to the PTU control valve. The FAA is proposing this AD to address the unsafe condition on these products.